抄録
The basic fatigue mechanism of reinforced concrete beams, which have the bars with a point of stress concentration, are showed by experiments and a theoretical analysis. The experiments are made by beams with a single steel bar and 3 steel bars. The analysis is done by the application of linear cumulative damage law. The results are as follows 1) The fatigue crack from a point of stress concentration at a bar of the beam spread to the other bars, accompanying stress redistribution. Concequently, the stress of the bar with initial crack decreases and the stress of the other bars increases. For that reason, the fatigue life of the beam becomes longer than that supposed by the experimental results of a bar. 2) The bars in the beam are loaded by changing stress range because of the stress redistribution between bars. The fatigue life of the material under changing stress range can be derived from linear cumulative damage law. Applying that law, the fatigue life of the beam is obtained as the life until all bars in the beam are fractured by the changing stress range.
